2 cams with same #s except for lift, why make the lower lift one at all?
Jun 14, 2006 | 10:21 PM
#1
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From: Forest Lake, MN
2 cams with same #s except for lift, why make the lower lift one at all?
Hello modders,
I am researching cams, and have found a couple to consider.
But why are some less lift than others?
I would think that until you hit the piston, more lift is better.
Please tell me why this isn't always true.
Thanks
BTW:
2006 L33, want good low end torque+ a decent redline (6200)
is it possible?
I am researching cams, and have found a couple to consider.
But why are some less lift than others?
I would think that until you hit the piston, more lift is better.
Please tell me why this isn't always true.
Thanks
BTW:
2006 L33, want good low end torque+ a decent redline (6200)
is it possible?
Jun 15, 2006 | 07:10 AM
#2
Im assuming that you are talking about the comp cam 212/218 cams?? there is a low lift version and a high lift version of them....
I used to have the low lift version and was shifting at 6200..
I used to have the low lift version and was shifting at 6200..
Jun 15, 2006 | 08:23 AM
#5
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In most cases, the cam with more lift will make more power, but not always.
Sometimes with an unported head(or a poorly ported one), you will see the cfm on the flow bench actually start decreasing at a certain lift. This is where the air is getting turbulant, and trying to change direction in the port.
In these cases, you will actually make more power by staying below the valve lift where the air gets turbulant.
There is also a optimum amout of lift for any engine combination to give you 100% V.E. at any given Peak Power RPM. If your engine only needs .600" lift to fill the cyl's at 7,000 rpm, putting .650" lift in will give you very little or no gain in power at 7,000 rpm. The very little gain in power may not be worth the added costs and maintanance and decrease in durability that are required to run the higher lift.
When you are looking at 2 cams that are the same @.050" but one has more lift, you also need to look at the seat duration to compare the two.
Sometimes the higher lift cam with the same .050" duration will have less seat duration. The smaller seat duration will cause the cam to make the torque and HP peaks at a lower RPM.
Sometimes with an unported head(or a poorly ported one), you will see the cfm on the flow bench actually start decreasing at a certain lift. This is where the air is getting turbulant, and trying to change direction in the port.
In these cases, you will actually make more power by staying below the valve lift where the air gets turbulant.
There is also a optimum amout of lift for any engine combination to give you 100% V.E. at any given Peak Power RPM. If your engine only needs .600" lift to fill the cyl's at 7,000 rpm, putting .650" lift in will give you very little or no gain in power at 7,000 rpm. The very little gain in power may not be worth the added costs and maintanance and decrease in durability that are required to run the higher lift.
When you are looking at 2 cams that are the same @.050" but one has more lift, you also need to look at the seat duration to compare the two.
Sometimes the higher lift cam with the same .050" duration will have less seat duration. The smaller seat duration will cause the cam to make the torque and HP peaks at a lower RPM.
Jun 15, 2006 | 09:05 PM
#6
Some folks like lower lift cams because they're kinder to the valve springs, allowing for longer spring life. Different people have different goals with their set-ups....some just want a nice improvement in power without beatin the crap out of their valvetrain 
I'm planning to run a fairly low lift cam when I build my 6.0...probably the Comp 216/220 .525/.532 114. I don't want to have to rev my engine to the moon, and I like being able to use LS6 springs.
I'm planning to run a fairly low lift cam when I build my 6.0...probably the Comp 216/220 .525/.532 114. I don't want to have to rev my engine to the moon, and I like being able to use LS6 springs.
Jun 16, 2006 | 01:08 AM
#7
Originally Posted by CamKing
In most cases, the cam with more lift will make more power, but not always.
Sometimes with an unported head(or a poorly ported one), you will see the cfm on the flow bench actually start decreasing at a certain lift. This is where the air is getting turbulant, and trying to change direction in the port.
In these cases, you will actually make more power by staying below the valve lift where the air gets turbulant.
There is also a optimum amout of lift for any engine combination to give you 100% V.E. at any given Peak Power RPM. If your engine only needs .600" lift to fill the cyl's at 7,000 rpm, putting .650" lift in will give you very little or no gain in power at 7,000 rpm. The very little gain in power may not be worth the added costs and maintanance and decrease in durability that are required to run the higher lift.
When you are looking at 2 cams that are the same @.050" but one has more lift, you also need to look at the seat duration to compare the two.
Sometimes the higher lift cam with the same .050" duration will have less seat duration. The smaller seat duration will cause the cam to make the torque and HP peaks at a lower RPM.
Sometimes with an unported head(or a poorly ported one), you will see the cfm on the flow bench actually start decreasing at a certain lift. This is where the air is getting turbulant, and trying to change direction in the port.
In these cases, you will actually make more power by staying below the valve lift where the air gets turbulant.
There is also a optimum amout of lift for any engine combination to give you 100% V.E. at any given Peak Power RPM. If your engine only needs .600" lift to fill the cyl's at 7,000 rpm, putting .650" lift in will give you very little or no gain in power at 7,000 rpm. The very little gain in power may not be worth the added costs and maintanance and decrease in durability that are required to run the higher lift.
When you are looking at 2 cams that are the same @.050" but one has more lift, you also need to look at the seat duration to compare the two.
Sometimes the higher lift cam with the same .050" duration will have less seat duration. The smaller seat duration will cause the cam to make the torque and HP peaks at a lower RPM.
great info, bigger isnt always better
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Jun 17, 2006 | 04:24 PM
#10
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From: From Houma La. Living n Ellisville Miss.
Originally Posted by CamKing
In most cases, the cam with more lift will make more power, but not always.
Sometimes with an unported head(or a poorly ported one), you will see the cfm on the flow bench actually start decreasing at a certain lift. This is where the air is getting turbulant, and trying to change direction in the port.
In these cases, you will actually make more power by staying below the valve lift where the air gets turbulant.
There is also a optimum amout of lift for any engine combination to give you 100% V.E. at any given Peak Power RPM. If your engine only needs .600" lift to fill the cyl's at 7,000 rpm, putting .650" lift in will give you very little or no gain in power at 7,000 rpm. The very little gain in power may not be worth the added costs and maintanance and decrease in durability that are required to run the higher lift.
When you are looking at 2 cams that are the same @.050" but one has more lift, you also need to look at the seat duration to compare the two.
Sometimes the higher lift cam with the same .050" duration will have less seat duration. The smaller seat duration will cause the cam to make the torque and HP peaks at a lower RPM.
Sometimes with an unported head(or a poorly ported one), you will see the cfm on the flow bench actually start decreasing at a certain lift. This is where the air is getting turbulant, and trying to change direction in the port.
In these cases, you will actually make more power by staying below the valve lift where the air gets turbulant.
There is also a optimum amout of lift for any engine combination to give you 100% V.E. at any given Peak Power RPM. If your engine only needs .600" lift to fill the cyl's at 7,000 rpm, putting .650" lift in will give you very little or no gain in power at 7,000 rpm. The very little gain in power may not be worth the added costs and maintanance and decrease in durability that are required to run the higher lift.
When you are looking at 2 cams that are the same @.050" but one has more lift, you also need to look at the seat duration to compare the two.
Sometimes the higher lift cam with the same .050" duration will have less seat duration. The smaller seat duration will cause the cam to make the torque and HP peaks at a lower RPM.
this is one thing i agree on some guys want a lot dur. and 110 ls with 560 to 580 lift i am running still the same came that was in the 5.3 and i think it is doing real good.
if i every change cams i will go with a custom gring cam witch cam motion r com will cut is a 216/220 565/570 on a 115 ls, this way i lose no bottom end and should pull to around 6500 and should not lope the motor out the truck.
good info cam king